cpuidle: tegra: Check whether PMC is ready

Check whether PMC is ready before proceeding with the cpuidle registration.
This fixes racing with the PMC driver probe order, which results in a
disabled deepest CC6 idling state if cpuidle driver is probed before the
PMC.
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/cpuidle/cpuidle-tegra.c

@@ -337,6 +337,9 @@ static void tegra_cpuidle_setup_tegra114_c7_state(void)
 
 static int tegra_cpuidle_probe(struct platform_device *pdev)
 {
+	if (tegra_pmc_get_suspend_mode() == TEGRA_SUSPEND_NOT_READY)
+		return -EPROBE_DEFER;
+
 	/* LP2 could be disabled in device-tree */
 	if (tegra_pmc_get_suspend_mode() < TEGRA_SUSPEND_LP2)
 		tegra_cpuidle_disable_state(TEGRA_CC6);